2.5. Foramen magnum investigations
Foramen magnum rim images for the studies (without mandibles) screened out using polysiloxane putty and processed in a C++ 2018 personal computer. Images were taken at 20 cm focal distance and processed with 24-bit depth BitMap extension (bmp_work_dll) at 4014 x 2944 pixels dimensions using Microsoft paint Application, as configured for SHAPE chain coder program (http://lbm.ab.a.u-tokyo.ac.jp/~iwata/shape/) (Iwata and Ukai, 2002); a coding system for describing biological shapes and closed contours. A total of 2064 chain coded landmark points were evaluated on the foramen magnum outlines (Kuhl and Giardina, 1982; Chen et al., 2000), a chain code assigned numerical values between 0 to 7 around the contour outlines before binarizing a full colored image to a two-colored image (Black and white). Scanned outlines were stored on a scale of 30 mm as a pair of (y, x) clockwise in Cartesian coordinates.